What are we doing?

Daivd with his harp. (Unknown 960AD) Both Jewish and Christians scriptures contain very early religious music, partly said to be written by David.

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Introduction

Music has been around since the history of mankind. However, where most of today’s music tends to be used for personal entertainment, it was often used to give praise to deities. But are there any musicological properties of a piece of music that make it specifically suitable for religious purpouses? Bach himself sometimes re-used his ‘pagan’ music for religious purposes and vice versa giving an important role to lyrics. However, we also know that Bach was a master in the writing of baroque affective music, indicating a carefull use of pitch, volume, tibre, and time for bringing music to it’s purposes. So, even if there is some overlap between musical sound of pagan and religious music, there might be some aspects which fit just better for one of them.

Method

To be able to answer the research question one has to compare religious music with non-religious music. This is implemented in R using the spotifyr module which gathers data from two types of playlists: religious and non-religious. Both corpuses are more usefull for machine learning purposes, as for example classification, if they contain many songs. Therefore, a set of different playlists which tend to be typically religious or non-religious has been made. Depending on the results, the religious playlists could be split up further to detect if there are any difference between different religions. Differences are measured between contemporary music lists but could be further expanded to more classical oriented music. Both sets are mostly biased with so called top-songs.

Data, data, data

Religious	Playlist ID	Songs	Non-religious Complement	Playlist ID	Songs	Balance
Religious	0IJbO5M2xD33mMHaeLRdSn	101	Non Religious	4VuiQ0wD6Xh5uDYveV2b0C	183	-97
Religious Songs	1Lfv5hpiBqtxHIlaeUo8TS	44	Non Religious 3	0B6Lj8siocfyTOCzyeBYzX	59
Christian Playlist for 2017	5t4HnPlX51s5ZdC2Lucnyz	391	Top 2017	1DoUPHRIAC6YbEPiDf8IOd	99	292
Top Christian Contemporary	37i9dQZF1DWUileP28ODwg	58	Today's Top Hits	37i9dQZF1DXcBWIGoYBM5M	50	8
Top Christian	37i9dQZF1DXcb6CQIjdqKy	66	TOP 2019	208tdAvqyrtssZFKLktwkx	43	23
Islamic Song	3SxT23r9nc6M1Ew2xrVpaV	108	Top Tracks of 2018	37i9dQZF1DX1HUbZS4LEyL	100	21
Islamic Songs	1YVnT9OowJP6ayM5QRazW7	120	Top of the Charts	7b2rMhQyuX3vkgQz2umhdV	107
Islamic / Nasheeds	1dNteyophghoFsbO3lCULn	67	Pop A Capella	6I3FnHFqsEwwifL63hX3gf	100	20
Fusion Hinduism	5lNmoVhBqIY0zKcZH3RZlr	53
Sanskrit / Hindu Mantra Chants	6RLNAQJoR5OUAl5lyA8YJJ	133	2019 Hits	4JkkvMpVl4lSioqQjeAL0q	128	5
Buddhist Meditation Songs	3c4AduB9UOrxkfdW0Nh2hA	270	Top allertijden	1nwCwjYUStN0xvoSmSgS9M	785	-22
BUDISTA	1aBpY65gFEM88trlD8Beht	238
Top Jewish Music	05Um5tgwbBWNAikYlwCId6	255
Jewish Music - Driving	1m0HB9PIDiovCDtO4qc00l	402	Driving Songs Everybody Likes	1prdy5Q62wxQ0Mb4gOOfeD	604	-202

Used playlists. Balance only compares the number of songs, not their duration. Playlist names might be altered and/or shortened for readability.

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What’s inside?

Using the most interesting whole-song features from the Spotify API, duration_ms and speechiness are on a re-normalized log scale.

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These visualisations show the spread of each musical variable. De cirle with cross shows where the mean lies. There are already some interesting findings visible like the difference in danceability of religious and non religious music. On average religious music is less danceable but more acoustic compared to non-religious music. Speechiness and duration are quite the same with exceptions to many outliers. On most properties Religious music has a very wide spread. Tempo is the same on average, however there is more spread in religious music.

The Key to Religion

Predicitions of the key of a piece of music according to Spotify. Keys are sorted on the most common of the whole corpus (both religious and non-religious music).

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Using spotify’s key_mode property one is able to visualize how the keys are distributed for different religions. Religious songs tend to use a bit more of C major. Jewish music is using many different keys while Christian music follows the sorting order of the whole data set more general. Buddhist and Hindu music also seem quite diverse. However the total difference in religious and non-religious music is not that big. Maybe we can get more from a more emotional view of music?

Religions Differ

All songs from the corpus on the AV-plane, size is popularity.

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On the arousal-valence plane religious and non-religious music have kind of the same spread, however there is a big difference for individual religions. Buddhistic music tends to be quite sleepy while most Jewish music tends to be very happy. Christian and Islamic music have a wider spread like non-religious music, where the former is in the more angry corner of the plane. The different musical modes do not have much influence on the emotional placement. These results point to a research direction which focuses more on different aspects of music of different religions. For now it seems that there is indeed a difference between religious and non-religious music. However it might also be that the differences are just the result of comparing western music with non-western music. To test that hypothesis Christian and Islamic songs have to be compared more thoroughly with the non-religious data set.

Outliers

Different aspects of an outlier.

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Let’s inspect some outliers of different religions.

• The buddhistic song has a very high valence combined with a very low energy. This piece does not seem to have a primary key, however there is some kind of pattern visible. There is also a small checkerboard visible on the pitch side indicating fast changes of pitch.
• The Jewish and None-religious songs have a very high valence and a very high energy They both have much of the c2 feature in the timbre. Also there seems to be a switch in pitch in both songs at two-third of the song.

Archetypes

Different aspects of some archetypes.

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These songs where selected based on their position on the AV-plane. They are closest to the mean of the energy and the mean of the valance of their group and represent the properties of a specific song central in their religious group.

TODO: interpretation

Learning Religions

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Using Random Forest on the whole dataset we get the following results:

So What?

Conclusion

There seems to be a lot of musical difference between different religions while for every religion there is some non-religious music available with kind of the same properties.

c_11 tends to be very descriptive in the difference between religious and non-religious music. Also, in this corpus religious music seems tho consist of songs of a longer duration compared to non religious music.

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